Survival Outcomes of Gemcitabine Plus S-1 Adjuvant Chemotherapy after Surgical Resection for Advanced Biliary Tract Cancer.

Background: The usefulness of adjuvant chemotherapy in biliary tract cancer (BTC) is poorly reported. This study aimed to evaluate the effectiveness and safety of adjuvant gemcitabine plus S-1 (GS) chemotherapy after curative surgical resection for BTC.

Methods: 225 BTC patients who underwent surgical resection between January 2006 and May 2019 were enrolled in this study. Twenty-seven patients received adjuvant chemotherapy with GS (GS group), whereas 67 patients underwent surgery alone (S group). Twenty-three matching pairs were derived through propensity score (PS) matching analysis. Patients received 12 cycles of adjuvant chemotherapy (70 mg/m2 oral S-1 for 7 consecutive days plus intravenous gemcitabine 1,000 mg/m2 on day 7). The primary end point was recurrence-free survival (RFS). The secondary end points were the 1-, 2-, and 3-year RFS and overall survival (OS) rates, tolerability, and frequency of grade 3/4 toxicity.

Results: The completion rate was 81.5%; no treatment-related deaths were observed. Grade 3/4 adverse events were seen in 40.7% of the patients. RFS (3-year RFS rate: 59.3% vs. 39.1%, p = 0.049) and OS (3-year OS rate: 71.7% vs. 53.4%, p = 0.008) were significantly better in the GS group than in the S group among PS-matched pairs.

Conclusions: GS chemotherapy after curative surgery was well tolerated, showed better clinical benefit in the adjuvant setting, and can effectively reduce BTC recurrence.